Essential oil was extracted by steam distillation from dry lemon leaves and fresh lemon leaves. The performance of essential oil from lemon leaf in scavenging free radicals, sodium nitrite and inhibiting xanthine oxidase activity were investigated. The results showed that the essential oil from fresh leaf has strong scavenging ability on hydroxyl radical and superoxide anion radical. The hydroxyl radical scavenging rate of the essential oil from fresh leaf was 90.72%, IC50 value was 4.27. The superoxide radical scavenging rate of the essential oil from fresh leaf was 73.49%, IC50 value was 5.17. the sodium nitrite scavenging rate of the essential oil from dry leaf oil was 89.55%, IC50 value was 4.19. The xanthine oxidase scavenging rate of ethyl acetate extraction of fresh lemon leaves was 89.12%. The scavenging ability between hydroxyl radical and NO2- of essential oil from lemon leaf has a significant correlation（P<0.05）. Moreover. The ability between the total reduction?and scavenging NO2- of essential oil from fresh lemon leaf has a?remarkabal significant correlation（P<0.01）.